NDI and Live Titling
by: Jan Ozer
/ Streaming Media
If you haven't been watching the live titling space, you've missed the NDI revolution, and your productions may be falling behind in terms of graphics quality. In this article I'll explain what NDI is and how it works. I'll explore how it enhances the titling capabilities of the NewTek TriCaster, Telestream Wirecast, and vMix GO. I'll also look at the base capabilities of each system and discuss when it's time to consider third-party offerings.
“Titles and graphics are absolutely integral to providing a high-quality experience,” says Mark Leblang, studio/live production manager for the Philadelphia Eagles. “In fact, there are no other production elements that can enhance a video presentation as much as high-quality graphics.” To incorporate graphics and titles into the Eagles’ live productions, Leblang uses two ChyronHego LyricIP systems (formerly named ChyronIP) connected to two NewTek TriCaster 8000 mixers running Advanced Edition.
While these systems may be too costly for many live event producers, the technology that powers the Lyric/TriCaster integration, called Network Device Interface (NDI). It now enables similar workflows on less expensive systems. If you haven’t been watching the live titling space, you’ve missed the revolution, and your productions may be falling behind in terms of graphics quality.
But don’t worry. I’ll explain what NDI is and how it works. I’ll explore how it enhances the titling capabilities of the NewTek TriCaster, Telestream Wirecast, and vMix GO. I’ll also look at the base capabilities of each system and explore when it’s time to consider third-party offerings.
NDI technology delivers extremely low-latency video streams over a local area network such as the 1Gbps Ethernet network in your office or studio. Previously, if you had two TriCaster systems in two different studios, you may have had to string an HD-SDI cable or fiber connection between them. Now, as long as the systems are connected on the same LAN, either system can send a stream to the other over the network.
NDI is not a new technology. NewTek has used NDI for years to enable complementary products to send content streams to the TriCaster for input via a network input in TriCaster. Now, NewTek has simply opened up the spec for others to use without any charge. In an interview in TV Technology, NewTek president and CTO Andrew Cross stated, “For years, we’ve had the ability to take video from a Vizrt virtual set system, for example, and send it over IP into a NewTek TriCaster. … We’ve been relatively open about giving anybody the ability to send us video. And we’ve had the SDK for a long time. What we’ve done now is [open] up all parts of this—the sending part is open, but now the receiving part is open. Even [to] those vendors making competitive products.”
Why would NewTek open up the spec? Basically, to promote IP-based video workflows, although the move benefits all producers of content creation products, as well as other live video mixers. It’s no surprise that Telestream has incorporated NDI into Wirecast while StudioCoast did the same for vMix. vMix is so excited about the new technology that if you Google “vMix NDI YouTube,” you’ll see more than 20 videos the company offers, discussing the technology and vMix’s implementation.
Under the hood, NDI uses discrete cosine transform (DCT), the technology used in JPEG, to compress the video signals. Sounds a lot like Motion JPEG or AVC-Intra. NewTek claims that an i7-based computer can compress a 1080p signal at 250 frames per second, with a peak signal-to-noise ratio (PSNR) value in excess of 70dB. According to NewTek, this will deliver similar quality to ProRes or Avid DNxHD. File bandwidth depends on resolution, frame rate, and content. But NewTek says, “For a typical 1080i HD stream, 100Mbps per stream is a reasonable bandwidth estimate.”
NDI supports all resolutions, frame rates, and video streams, with and without alpha channel. NewTek expects most implementations to utilize 8-bit UYVY and RGBA video, though support for 10-bit and 16-bit is available. Once encoded into the NDI format, the video stays in the format until the final rendering, which NewTek calls “multigenerational stability.”
Working With NDI
NDI can be used for many purposes, including allowing titling products to communicate with live-switchers, which is our focus here. Looking beyond titling for a moment, NewTek has written a number of drivers and applications that enable computers to perform a variety of applications. From working as a telestrator to ISO recording, to allowing any computer to send between two and four streams from a webcam or camera/capture card to a TriCaster.
Figure 1 (right)
shows a title created in After Effects sent to an NDI monitor on the same system. As you’ll see in Figure 5, vMix version 17, which is NDI-compatible. You could import this stream, as well as TriCaster or any other NDI-compatible station on the same LAN. This essentially converts After Effects into a live titling engine. And it turns Adobe Premiere Pro CC into a highly flexible playout device. I’ll explore this function in more detail later.
Figure 1. Sending out an After Effects title via NDI: See this being received by vMix in Figure 4. Click this image to see it at full size.
Clearly, NDI is an exciting technology that will have a profound impact on all aspects of live production. For now, let’s resume our focus on titling, starting with the TriCaster.
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